Opinionated OCaml linter with Merlin integration for code quality, naming conventions, and style checks
merlint: add E520 (lib/ convention) and E521 (cram under test/cram/)
Two project-structure rules:
- E520 flags packages whose library code lives in src/ (the monorepo
convention is lib/, used by 155+ packages). Auto-fix: git mv src lib.
- E521 flags cram tests (.t files or .t directories with run.t) at
test/ rather than test/cram/. Shared driver exes belong in
test/cram/helpers/; shell setup in test/cram/helpers.sh sourced via
(setup_scripts helpers.sh).
+227
+2
lib/data.ml
+2
lib/data.ml
+43
lib/rules/e520.ml
+43
lib/rules/e520.ml
···
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(** E520: Package library directory should be named lib/, not src/.
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The monorepo convention is that a package's primary library lives under
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[lib/]. Older packages that still use [src/] must be renamed. *)
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type payload = { package : string }
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let check (ctx : Context.project) =
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let root = ctx.project_root in
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let try_readdir d =
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try Sys.readdir d |> Array.to_list with Sys_error _ -> []
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in
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let issues = ref [] in
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let packages = try_readdir root in
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List.iter
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(fun pkg ->
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let pkg_dir = Filename.concat root pkg in
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if
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Sys.file_exists pkg_dir && Sys.is_directory pkg_dir && pkg <> "_build"
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&& pkg <> ".git" && pkg <> "_opam"
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then
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let src_dir = Filename.concat pkg_dir "src" in
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let has_ml f = Filename.check_suffix f ".ml" in
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if Sys.file_exists src_dir && Sys.is_directory src_dir then
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let src_has_ml = List.exists has_ml (try_readdir src_dir) in
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if src_has_ml then issues := Issue.v { package = pkg } :: !issues)
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packages;
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!issues
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let pp ppf { package } =
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Fmt.pf ppf
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"%s uses src/ for its library; rename to lib/ to match the monorepo \
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convention"
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package
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let rule =
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Rule.v ~code:"E520" ~title:"Library directory should be lib/, not src/"
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~category:Rule.Project_structure
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~hint:
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"The monorepo convention is lib/ for library code. Rename src/ to lib/ \
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with `git mv`; no dune changes are needed because dune auto-discovers \
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modules in either directory."
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~examples:[] ~pp (Project check)
+62
lib/rules/e521.ml
+62
lib/rules/e521.ml
···
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(** E521: Cram tests belong under test/cram/, not scattered in test/.
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The monorepo convention is that all cram tests for a package live under
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[<package>/test/cram/]:
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{v
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test/cram/
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├── dune # one (cram ...) stanza
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├── helpers.sh # auto-sourced, exports PATH etc.
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├── helpers/ # driver exe sources
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│ ├── dune
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│ └── demo.ml
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└── cli.t/
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└── run.t
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v}
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This rule flags cram tests (.t files or .t directories containing run.t)
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that sit directly in test/ rather than under test/cram/. *)
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type payload = { package : string; path : string }
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let check (ctx : Context.project) =
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let root = ctx.project_root in
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let try_readdir d =
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try Sys.readdir d |> Array.to_list with Sys_error _ -> []
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in
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let issues = ref [] in
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let packages = try_readdir root in
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List.iter
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(fun pkg ->
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let test_dir = Filename.concat (Filename.concat root pkg) "test" in
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let is_cram name full =
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Filename.check_suffix name ".t"
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&& ((not (Sys.is_directory full && Sys.file_exists full))
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|| Sys.file_exists (Filename.concat full "run.t"))
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in
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if pkg <> "_build" && pkg <> "_opam" && Sys.file_exists test_dir then
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let entries = try_readdir test_dir in
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List.iter
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(fun name ->
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let full = Filename.concat test_dir name in
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let ok = try is_cram name full with Sys_error _ -> false in
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if ok then
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issues :=
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Issue.v { package = pkg; path = Filename.concat "test" name }
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:: !issues)
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entries)
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packages;
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!issues
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let pp ppf { package; path } =
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Fmt.pf ppf "%s/%s should live under %s/test/cram/" package path package
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let rule =
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Rule.v ~code:"E521" ~title:"Cram test outside test/cram/"
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~category:Rule.Project_structure
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~hint:
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"Move cram tests (.t files or .t/ directories) under the package's \
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test/cram/ umbrella. Shared driver exes go in test/cram/helpers/; shell \
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setup goes in test/cram/helpers.sh (sourced via (setup_scripts \
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helpers.sh))."
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~examples:[] ~pp (Project check)
+1
test/cram/e520.t/bad/dune-project
+1
test/cram/e520.t/bad/dune-project
···
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(lang dune 3.21)
+1
test/cram/e520.t/bad/pkg/src/a.ml
+1
test/cram/e520.t/bad/pkg/src/a.ml
···
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let _ = ()
+1
test/cram/e520.t/good/dune-project
+1
test/cram/e520.t/good/dune-project
···
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(lang dune 3.21)
+1
test/cram/e520.t/good/pkg/lib/a.ml
+1
test/cram/e520.t/good/pkg/lib/a.ml
···
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let _ = ()
+56
test/cram/e520.t/run.t
+56
test/cram/e520.t/run.t
···
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Test bad example - package uses src/ instead of lib/:
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$ merlint -B -r E520 bad/
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Running merlint analysis...
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Analyzing 0 files
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✓ Code Quality (0 total issues)
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✓ Code Style (0 total issues)
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✓ Naming Conventions (0 total issues)
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✓ Documentation (0 total issues)
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✗ Project Structure (1 total issues)
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[E520] Library directory should be lib/, not src/ (1 issue)
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The monorepo convention is lib/ for library code. Rename src/ to lib/ with
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`git mv`; no dune changes are needed because dune auto-discovers modules in
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either directory.
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- (global) pkg uses src/ for its library; rename to lib/ to match the monorepo convention
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✓ Test Quality (0 total issues)
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✓ Interop Testing (0 total issues)
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✓ Code Generation (0 total issues)
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╭───────────────────┬──────────────────────────────────────────────────╮
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│ Category │ Issues │
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├───────────────────┼──────────────────────────────────────────────────┤
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│ Project Structure │ 1 (1 library directory should be lib/, not src/) │
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╰───────────────────┴──────────────────────────────────────────────────╯
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Summary: ✗ 1 total issue (applied 1 rule)
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✗ Some checks failed. See details above.
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[1]
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Test good example - package uses lib/:
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$ merlint -B -r E520 good/
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Running merlint analysis...
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Analyzing 0 files
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✓ Code Quality (0 total issues)
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✓ Code Style (0 total issues)
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✓ Naming Conventions (0 total issues)
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✓ Documentation (0 total issues)
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✓ Project Structure (0 total issues)
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✓ Test Quality (0 total issues)
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✓ Interop Testing (0 total issues)
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✓ Code Generation (0 total issues)
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Summary: ✓ 0 total issues (applied 1 rule)
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✓ All checks passed!
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+1
test/cram/e521.t/bad/dune-project
+1
test/cram/e521.t/bad/dune-project
···
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(lang dune 3.21)
+1
test/cram/e521.t/bad/pkg/test/foo.t/run.t
+1
test/cram/e521.t/bad/pkg/test/foo.t/run.t
···
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$ echo ok
+1
test/cram/e521.t/good/dune-project
+1
test/cram/e521.t/good/dune-project
···
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(lang dune 3.21)
+1
test/cram/e521.t/good/pkg/test/cram/foo.t/run.t
+1
test/cram/e521.t/good/pkg/test/cram/foo.t/run.t
···
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$ echo ok
+56
test/cram/e521.t/run.t
+56
test/cram/e521.t/run.t
···
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Test bad example - cram test at test/ rather than test/cram/:
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$ merlint -B -r E521 bad/
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Running merlint analysis...
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Analyzing 0 files
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✓ Code Quality (0 total issues)
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✓ Code Style (0 total issues)
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✓ Naming Conventions (0 total issues)
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✓ Documentation (0 total issues)
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✗ Project Structure (1 total issues)
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[E521] Cram test outside test/cram/ (1 issue)
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Move cram tests (.t files or .t/ directories) under the package's test/cram/
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umbrella. Shared driver exes go in test/cram/helpers/; shell setup goes in
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test/cram/helpers.sh (sourced via (setup_scripts helpers.sh)).
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- (global) pkg/test/foo.t should live under pkg/test/cram/
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✓ Test Quality (0 total issues)
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✓ Interop Testing (0 total issues)
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✓ Code Generation (0 total issues)
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╭───────────────────┬────────────────────────────────────╮
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│ Category │ Issues │
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├───────────────────┼────────────────────────────────────┤
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│ Project Structure │ 1 (1 cram test outside test/cram/) │
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╰───────────────────┴────────────────────────────────────╯
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Summary: ✗ 1 total issue (applied 1 rule)
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✗ Some checks failed. See details above.
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[1]
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Test good example - cram test under test/cram/:
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$ merlint -B -r E521 good/
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Running merlint analysis...
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Analyzing 0 files
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✓ Code Quality (0 total issues)
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✓ Code Style (0 total issues)
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+
✓ Naming Conventions (0 total issues)
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+
✓ Documentation (0 total issues)
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+
✓ Project Structure (0 total issues)
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✓ Test Quality (0 total issues)
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✓ Interop Testing (0 total issues)
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✓ Code Generation (0 total issues)
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Summary: ✓ 0 total issues (applied 1 rule)
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✓ All checks passed!
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